Start by preheating your oven to 450ºF and generously apply cooking spray to the muffin pan cups.
If using a mini muffin pan, place 2-3 tater tots in each cup; for a regular muffin pan, fit 4-5 tater tots per cup.
Bake the muffin pan on the bottom rack for approximately 10 minutes, then remove it from the oven.
Using a shot glass or small juice glass, spray with cooking spray and twist it into the center of each muffin cup to form potato cups. Return the pan to the oven and bake for an additional 15 minutes, or until golden brown.
Top each potato cup with a tablespoon of cheese and bake for another 4-5 minutes, until the cheese is melted. Allow cooling on a platter for 5 minutes.
Add a dollop of sour cream, a sprinkle of crumbled bacon, and green onions on each cup before serving warm.